Strontium isotope systematics of conodonts: Middle Devonian, Eifel Mountains, Germany

Ebneth, Stefan; Diener, Andreas; Buhl, Dieter; Veizer, Ján

doi:10.1016/s0031-0182(97)00057-6

Cited by 44 publications

(22 citation statements)

References 35 publications

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“…This agrees with the diagenetic modifications in the geochemical/isotopic composition of conodonts with CAI values < 2 described by Holmden et al (1996), Ebneth et al (1997) and John, Cliff & Wignall (2008).…”

Section: Discussionsupporting

confidence: 91%

Conodont alteration and tectonothermal evolution of a diagenetic unit in the Iberian Variscan belt (Ponga-Cuera unit, NW Spain)

et al. 2010

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-Tectonothermal analysis of a mainly carbonate unit located in the external part of the Variscan orogen in NW Spain is dealt with using the conodont colour alteration index (CAI) and the study of textures of these microfossils. The Kübler index of the illite (KI) is used as a complementary method. The area is characterized by a great uniformity in the CAI values, which in most cases are < 2, indicating diagenetic conditions. In spite of the low CAI values, textures show great variety and were mainly originated by diagenetic processes of apatite dissolution and precipitation. The conodonts underwent a long period of heating (probably from the Pennsylvanian to the Cenozoic) to low temperatures (< 100• C) to reach the low CAI values measured. Assuming a normal geothermal gradient, these temperatures required an overburden < 3 km that in part was due to burial and in part to tectonic superimposition. Minor local anomalies in the CAI values and some textural alterations, related to dissolution and precipitation of authigenic minerals, could be due to epithermal activity that gave rise to various ore deposits in the studied area mainly during Permian times.

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Section: Discussionsupporting

confidence: 91%

Conodont alteration and tectonothermal evolution of a diagenetic unit in the Iberian Variscan belt (Ponga-Cuera unit, NW Spain)

et al. 2010

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“…Grandjean et al (1987) used REE profiles in ichthyoliths to reconstruct palaeobathymetry and changes in ocean circulation. Bertram et al (1992) showed conodont apatite recorded ancient seawater 87 Sr/ 86 Sr values but samples with a conodont colour alteration index above 2.5 were suspect and even those below CAI 2.5 may be suspect, similar findings have been confirmed by other investigators (Diener et al, 1996;Ebneth et al, 1997;Veizer et al, 1999). Reynard et al (1999) modelled the crystal-chemical controls on REE uptake by apatite from water by extrapolation of mineral/melt partition coefficients to lower temperature environments.…”

Section: Introductionmentioning

confidence: 62%

“…Bertram et al (1992) found that conodonts of the same age with low CAI values have much lower 87 Sr/ 86 Sr ratios than samples with high CAI values. They concluded that the process of thermal maturation had resulted in the incorporation of Sr into the conodont lattice that is more radiogenic than the seawater, by exchange with diagenetic fluids; a conclusion supported by more recent studies (Diener et al, 1996;Ebneth et al, 1997;Veizer et al, 1999). Textural and proton-induced X-ray emission (PIXE) trace element studies (Bruhn et al, 1997) have showed that conodonts exchange about one third of their Sr with the surrounding rock matrix.…”

Section: Strontium Isotopesmentioning

confidence: 96%

“…Textural and proton-induced X-ray emission (PIXE) trace element studies (Bruhn et al, 1997) have showed that conodonts exchange about one third of their Sr with the surrounding rock matrix. In pure carbonates they may still retain their near seawater 87 Sr/ 86 Sr values, but mostly values are ϳ5 ϫ 10 Ϫ5 more radiogenic (Ebneth et al, 1997). The strontium isotope record as measured in calcitic brachiopods shows an Early Carboniferous decline from ϳ0.7083 to a mid-Visean minimum of 0.7077 followed by a sharp rise to the mid-Pennsylvanian (Bruckschen et al, 1995;Bruckschen et al, 1999).…”

Section: Strontium Isotopesmentioning

confidence: 99%

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Thermal effects on rare earth element and strontium isotope chemistry in single conodont elements

Armstrong

Pearson

Griselin

2001

Geochimica et Cosmochimica Acta

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Abstract-A low-blank, high sensitivity isotope dilution, ICP-MS analytical technique has been used to obtain REE abundance data from single conodont elements weighing as little as 5 g. Sr isotopes can also be measured from the column eluants enabling Sr isotope ratios and REE abundance to be determined from the same dissolution. Results are comparable to published analyses comprising tens to hundreds of elements.To study the effects of thermal metamorphism on REE and strontium mobility in conodonts, samples were selected from a single bed adjacent to a basaltic dyke and from the internationally used colour alteration index (CAI) "standard set." Our analyses span the range of CAI 1 to 8. Homogeneous REE patterns, "bell-shaped" shale-normalised REE patterns are observed across the range of CAI 1 to 6 in both sample sets. This pattern is interpreted as the result of adsorption during early diagenesis and could reflect original seawater chemistry. Above CAI 6 REE patterns become less predictable and perturbations from the typical REE pattern are likely to be due to the onset of apatite recrystallisation. Samples outside the contact aureole of the dyke have a mean 87 Sr/ 86 Sr ratio of 0.708165, within the broad range of published mid-Carboniferous seawater values. Our analysis indicates conodonts up to CAI 6 record primary geochemical signals that may be a proxy for ancient seawater.

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“…conodonts) that were checked for sample preservation (e.g. Jurassic: Jones et al 1994;Triassic: Martin & Macdougall 1995;Korte et al 2003Korte et al , 2004Permian: Martin & Macdougall 1995;Korte et al 2004Korte et al , 2006Carboniferous: Bruckschen et al 1999;Devonian: Diener et al 1996;Ebneth et al 1997;Ordovician: Shields et al 2003). Such macrofossil remains are thought to be comparatively resistant to diagenesis (Veizer 1989;Blake et al 1997;Veizer et al 1999;Zazzo et al 2004), representing therefore the most robust available archives for past seawater 87 Sr/ 86 Sr (e.g.…”

mentioning

confidence: 99%

Permian strontium isotope stratigraphy

Korte

Ullmann

2016

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Abstract:The secular evolution of the Permian seawater 87 Sr/ 86 Sr ratios carries information about global tectonic processes, palaeoclimate and palaeoenvironments, such as occurred during the Early Permian deglaciation, the formation of Pangaea and the Permian-Triassic (P-Tr) mass extinction. Besides this application for discovering geological aspects of Earth history, the marine 87Sr/86Sr curve can also be used for robust correlations when other bio-, litho-and/or chemostratigraphic markers are inadequate. The accuracy of marine 87 Sr/ 86 Sr reconstructions, however, depends on high-quality age control of the reference data, and on sample preservation, both of which generally deteriorate with the age of the studied interval. The first-order Permian seawater 87 Sr/ 86 Sr trend shows a monotonous decline from approximately 0.7080 in the earliest Permian (Asselian) to approximately 0.7069 in the latest Guadalupian (Capitanian), followed by a steepening increase from the latest Guadalupian towards the P-Tr boundary (c. 0.7071-0.7072) and into the Early Triassic. Various higher-order changes in slope of the Permian 87 Sr/ 86 Sr curve are indicated, but cannot currently be verified owing to a lack of sample coverage and significant disagreement of published 87 Sr/ 86 Sr records.

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Strontium isotope systematics of conodonts: Middle Devonian, Eifel Mountains, Germany

Cited by 44 publications

References 35 publications

Conodont alteration and tectonothermal evolution of a diagenetic unit in the Iberian Variscan belt (Ponga-Cuera unit, NW Spain)

Conodont alteration and tectonothermal evolution of a diagenetic unit in the Iberian Variscan belt (Ponga-Cuera unit, NW Spain)

Thermal effects on rare earth element and strontium isotope chemistry in single conodont elements

Permian strontium isotope stratigraphy

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